Many pickup trucks are fitted with a cover or cap which has a window on the rear. The cap covers the bed of the pickup truck. The window is generally hinged at the top and has a retaining device to hold the window in an open position. The window may also be of the drop glass type, i.e., where the glass may be retracted within the body or door panel of the vehicle to open the window and many be extended into the window opening to close the window. In many instances, it is desirable that a windshield wiper unit be utilized to wipe and clean the rear window when the window is in a closed position. This is because the rear window has a tendency to become deposited with contaminants and rain water that obscure the rear field of vision.
It is also desirable that the rear window be able to be opened despite the presence of the windshield wiper. This can be accomplished by parking the wiper blade in a parked position where it is out of contact with the window. Certain prior devices have provided a windshield wiper, which when in a parked position off the window, does not obstruct the opening of the rear window. Two such devices are disclosed in U.S. Pat. Nos. 3,019,468 and 3,670,353. In both of these patents, the wipers are guided from an operative position on the window to a parked position off the window and onto the frame. The cam or ramp is necessary because the window glass is frequently recessed relative to the frame to provide a space into which a molded air and liquid seal is fitted. As a consequence, any wiper system fitted to such a window must be capable of movement with two degrees of freedom, i.e., through the dimension of recess or hinge and through the wipe pattern on the glass surface. With the wiper off the window, the window can be opened.
Furthermore, it is desirable that because of the large number of existing truck caps that do not have rear windshield wiper systems that are already in existence, that a new wiper system be retrofitable on the vast majority of existing truck caps. One problem encountered in the retrofit of such windshield wiper systems is that the hinge(s) which attach the window to the frame, or the recess, frequently interfere with the movement of wiper blade onto the frame of the truck cap as might integral rain gutters or sealing mechanisms or the like. Therefore, it is highly desirable that the windshield wiper be able to be moved to a parked position despite the existence of hinges which protrude outwardly beyond the rear window or despite the existence of the recess. It is also important that such a device, in order to be retrofitable, be able to accommodate various truck cap geometries.
It is also desirable to mount the window wiper system through the glass pane or through the window frame such that the window wiper and motor are movable along with the glass pane.